[R] hurdle control and optim

[Matt Dicken]

I was hoping someone may be able to help with the following.

I fit the model below using the pscl package. I am modelling catch data (about 17,000 entry points) so lots of zero's

fit.hurdle.bin = hurdle(Catch ~ Beach + Region + Year+
                      Decade + Month + Season + Whale+ Sex + Size+ meantemp +
                      meanviz + offset(log(Length.nets..km.)),
                      dist="poisson",zero.dist="binomial",link="logit",trace=T)

The model output tells me that:
Warning message: In sqrt(diag(object$vcov)) : NaNs produced (against year)

I then use hurdle control with "L-BFGS-B" to set some parameter controls to solve this issue, but get the warning message:
L-BFGS-B needs finite values of 'fn'
In addition: Warning message:
In optim(fn = countDist, gr = countGrad, par = c(start$count, if (dist ==  :
  method L-BFGS-B uses 'factr' (and 'pgtol') instead of 'reltol' and 'abstol'

How do I write the script for Hurdle control to solve these issues?
Any help would be really appreciated
All the best
Matt





Dr. Matt Dicken
Senior Scientist
Telephone: 0315660400 | Fax: 0315660493 | Email: matt at shark.co.za
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